Synergistic interactions between the genetically modified bacterial polysaccharide P2 and carob or konjac mannan

Rheological studies have confirmed that the bacterial polysaccharide P2, a genetically modified variant of the Acetobacter xylinum polysaccharide acetan, undergoes synergistic gelation with either of the plant polysaccharides carob or konjac mannan. X-ray fibre diffraction data shows that P2 can form a 5-fold helical structure of pitch 4.7nm and an axial rise per disaccharide repeat of 0.92nm. Optical rotation data demonstrate that P2 undergoes a coil-helix transition in solution and that deacylation enhances the stability of the helical structure in solution. Studies made on mixtures prepared at different temperatures and ionic strengths suggest that denaturation of the P2 helix favours interaction and gelation. Deacetylation of P2 enhances gelation. X-ray diffraction data for oriented fibres prepared from deacetylated P2-konjac mannan mixed films reveal a 6-fold helical structure of pitch 5.54nm with an axial rise per disaccharide repeat also of 0.92nm. This mixed helix provides direct evidence for binding between the two polysaccharides. P2 contains two sites of acetylation: one on the backbone and one on the sidechain. The former site of acetylation inhibits helix formation for P2. It is suggested that this site of acetylation also inhibits formation of the mixed helix, explaining the enhanced gelation of mixtures on deacetylation.     

魔芋葡甘聚糖水溶胶的粘度行为研究

对魔芋葡甘聚糖(KGM)水溶胶在不同剪切速率、浓度、放置时间、温度等条件下的粘度行为进行了研究.结果表明,水溶胶的粘度随着剪切速率的增加而呈指数降低,属于非牛顿流体,1%的KGM水溶胶粘度η(10-4mpa·s)与剪切速率γ(s-1)的经验公式为η=1.41+9.04e-γ/0.107;粘度η(10-4mpa·s)随KGM质量分数ω(%)增加而呈指数增加,二者关系符合η=3.88eω/0.632;1%的KGM水溶胶粘度η(10-4mpa·s)随放置时间t(h)的增加而下降,可用多项关系式η=4.93+0.027t-5.15×10-4t2来拟合;温度升高则粘度会下降,1%的KGM水溶胶的粘流活化能为14.90 kJ/mol.此外,还分别探讨了不同电解质(如NaCl,NaOH,HCl)及表面活性剂(如CTAB,SDS,Tween 80)等对KGM水溶胶粘度的影响规律.     

双胶润通胶囊润肠通便功能的研究

目的:探讨双胶润通胶囊的润肠通便作用的效果及剂量.方法:实验采用动物试验,将小白鼠(雌雄各半,体重18～22 g)分成两个实验组,每组50只,实验一组进行小肠推进试验,实验二组进行排便试验,时间均为7 d.按推荐剂量每人每日5 g设计,分为低、中、高3个剂量组,另设空白对照和模型对照组.结果:在不影响小鼠体重的情况下,双胶润通胶囊高剂量组小肠推进率与模型对照组比较差异均有显著性变化(P《0.05);3个剂量组小鼠的首便时间、粪便粒数均高于便秘模型对照组,差异具有极显著性差异(P《0.01);结论:双胶润通胶囊对小鼠小肠运动有增强作用,并能缩短小鼠首便时间、增加小鼠的粪便粒数与重量,即:具有润肠通便作用.     

魔芋葡甘露寡糖的制备、化学结构及对胰岛NO自由基释放量的影响

魔芋精粉经 β 甘露聚糖酶酶解成寡糖后 ,用活性炭柱进行分离纯化 ,以不同浓度 (5 % ,10 % ,2 0 % )的乙醇洗脱 .研究不同洗脱组分对链脲佐菌素 (STZ)诱导糖尿病模型的胰岛NO自由基释放量的影响 .发现 1mg ml以 5 %乙醇洗脱的寡糖可以使胰岛培养液中的NO自由基释放量平均下降2 5 4 % (P <0 0 5 ) ,0 1mg ml以 5 %乙醇洗脱的寡糖使NO自由基水平下降 2 0 % (P <0 0 5 ) .结果表明 ,5 %乙醇洗脱的魔芋寡糖对保护胰岛免受链脲佐菌素 (STZ)的破坏有一定的作用 .用凝胶色谱、红外光谱、元素分析、核磁共振光谱、质谱等方法初步分析了 5 %乙醇洗脱的魔芋寡糖的化学结构 .发现该糖是一种四糖 ,分子量为 6 6 6 .其推测性结构式为 :β D Man(1→ 4 ) β D Man(1→ 4 ) β D Glc(1→ 4 )α D Man ,β D Man(1→ 4 ) β D Glc(1→ 4 ) β D Man(1→ 4 )α D Man或 β D Glc(1→ 4 ) β D Man(1→4 ) β D Man(1→ 4 )α D Man .     

SiO2‐Enhanced Structural Stability and Strong Adhesion with a New Binder of Konjac Glucomannan Enables Stable Cycling of Silicon Anodes for Lithium‐Ion Batteries

Silicon‐based anodes with high theoretical capacity have intriguing potential applications for next‐generation high‐energy lithium‐ion batteries, but suffer from huge volumetric change that causes pulverization of electrodes. Rational design and construction of effective electrode structures combined with versatile binders remain a significant challenge. Here, a unique natural binder of konjac glucomannan (KGM) is developed and an amorphous protective layer of SiO₂ is fabricated on the surface of Si nanoparticles (Si@SiO₂) to enhance the adhesion. Benefiting from a plethora of hydroxyl groups, the KGM binder with inherently high adhesion and superior mechanical properties provides abundant contact sites to active materials. Molecular mechanics simulations and experimental results demonstrate that the enhanced adhesion between KGM and Si@SiO₂ can bond the particles tightly to form a robust electrode. In addition to bridging KGM molecules, the SiO₂‐functionalized surface may serve as a buffer layer to alleviate the stresses of Si nanoparticles resulting from the volume change. The as‐fabricated KGM/Si@SiO₂ electrode exhibits outstanding structural stability upon long‐term cycles. A highly reversible capacity of 1278 mAh g^?1 can be achieved over 1000 cycles at a current density of 2 A g^?1, and the capacity decay is as small as 0.056% per cycle.     

A solid state NMR study of locust bean gum galactomannan and Konjac glucomannan gels

This paper describes a ¹³C solid state NMR study of hydrated powders and gels of locust bean gum galactomannan-LBG and Konjac glucomannan-KGM. Changes in relative spectral intensities, cross-polarization dynamics (T_CH, T_1ρH) and relaxation times (T_1C, T_1H, T_2H) show that hydration (0–90%) of LBG powders increases the 10⁸ Hz frequency molecular motions, probably reflecting the enhanced motion of non-aggregating segments and chain ends. Slower motions (10⁴–10⁵ Hz) are enhanced only slightly at 90% hydration. LBG gel shows higher spatial distinction between aggregated and non-aggregated segments than the hydrated powder and relaxation times indicate higher mobility for galactose-ramified segments, compared to linear mannose segments. While the dynamics of KGM hydration is similar to that of LBG, i.e. mainly affecting fast 10⁸ Hz motions, the gel is significantly more rigid. Both spectra and relaxation times show that glucose residues in KGM gel are particularly hindered, probably due to their preferential involvement in chain aggregation.     

Soluble glucomannan isolated from Candida utilis primes blood phagocytes

It is well documented that the polysaccharide glucomannan (GM), an abundant constituent of the fungal cell wall, in the form of particulate induces strong activation of phagocytes, however, the effects of soluble GM are not known. Activation of phagocyte anti-microbial mechanisms is a crucial part of the innate host defense against invading pathogens. However, under uncontrolled inflammatory conditions they contribute to damage of surrounding tissues. Thus, to prevent these deleterious effects, the activation of phagocytes is a tightly regulated process. Therefore, in this study we analyzed the effect of soluble GM on some neutrophil functions such as reactive oxygen species production, degranulation, and receptor mobilization at the plasma membrane. Soluble GM at the tested concentrations did not stimulate oxidative burst of phagocytes directly but significantly potentiated oxidative burst in response to opsonized zymosan particles. GM induced significant phosphorylation of p47phox subunit of NADPH oxidase on Ser345. This priming effect of GM was accompanied by time and concentration dependent degranulation characterized by increased surface expression of receptors stored in neutrophil granules (CD10, CD11b, CD14, CD35, and CD66b). Degranulation was further confirmed by increase of elastase activity in media. Thus, it could be suggested that soluble GM induces priming of phagocytes connected with their degranulation, the increase of surface receptor expression, and potentiation of oxidative burst response to opsonized particles through the activation of NADPH oxidase.     

魔芋接枝丙烯酸高吸水性树脂的制备及性能研究

本实验以魔芋精粉为基体,环己烷为连续相,Span-60为分散剂,硝酸铈铵为引发剂、用反相悬浮聚合法合成魔芋-丙烯酸高吸水性树脂。研究了多种因素对接枝共聚物吸水性能的影响。结果表明:反应时间为2 h、魔芋精粉与丙烯酸质量比为1∶5、交联剂用量为物料质量的0.04%、引发剂为3×10-3mol/L、丙烯酸中和度为60%、反应温度为70℃时,接枝共聚物吸水性能最优。并通过对接枝产物的红外图谱分析,证实了反应的可行性。     

魔芋葡甘低聚糖对小鼠抗氧化酶活性的影响

研究魔芋葡甘低聚糖对小鼠血浆和肝脏中抗氧化酶活性的影响。魔芋葡甘低聚糖能有效地降低肝脏中丙二醛(MDA)的含量,提高肝脏和血浆中超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-PX)的活性。尤以高剂量组效果最好。